Both of you are coming vague. His “leaning more hetero at the time” and your emphasis on ACTUALLY, you sound like you’re doubting that a person can like penises and vaginas, or just straight up not care.

He’s probably bi or pan. Probably always had been. He probably didn’t realize it in school, or wouldn’t admit it to himself due to societal pressure. He seems to be more comfortable about it now. It really doesn’t need much more detail.